Flame-retardant olefinic resin compositions

Abstract

A flame-retardant olefinic resin composition comprising (1) 100 parts by weight of an ethylenic polymer resin mixture having an average density of 0.890 to 0.915 g/cm 3 , of (a) an ethylenic polymer consisting mainly of an ethylene-alpha-olefin copolymer and (b) a silane-grafted polymer obtained by grafting a silane to at least one component of said ethylenic polymer (a), and (2) 50 to 300 parts by weight of a hydrated metal compound.

We claim: 
     
       1. A flame-retardant olefinic resin composition comprising the product of reacting component ( 1) with component (2) essentially in the absence of both of the following: a free-radical generator and a catalytic accelerator;   wherein components (1) and (2) are as follows: (1) 100 parts by weight of an ethylenic polymer resin mixture having an average density of 0.890 to 0.915 g/cm 3 , of: (a) an ethylenic polymer consisting mainly of an ethylene-alpha-olefin copolymer, and   (b) at least 2% based on the total weight of (a) and (b) of a silane-grafted polymer obtained by grafting a silane to at least one component of said ethylenic polymer (a), and     (2) 50 to 300 parts by weight of a hydrated metal compound whereby hydrolytic condensation occurs between said hydrated metal compound and said silane grafted polymer to form siloxane linkages between the metal of said hydrated metal compound and silanol groups of said silane-grafted polymer.     
     
     
       2. A flame-retardant olefinic resin composition according to claim 1, wherein the alpha-olefin is propylene, butene-1, pentene-1, 4-methylpentene-1, hexene or octene. 
     
     
       3. A flame-retardant olefinic resin composition according to claim 2, wherein the ethylene-alpha-olefin copolymer is a linear low density polyethylene or a very low density polyethylene. 
     
     
       4. A flame-retardant olefinic resin composition according to claim 1, wherein the silane-grafted polymer is obtained by reacting at least one component of said ethylenic polymer (a) with an organic silane represented by the general formula RR'SiY 2  wherein R is a monovalent olefinically unsaturated hydrocarbon group; Y is a hydrolyzable organic group; and R' is a monovalent hydrocarbon group other than unsaturated aliphatic hydrocarbon groups or is same as Y in the presence of a free-radical-generating compound. 
     
     
       5. A flame-retardant olefinic resin composition according to claim 1, wherein the hydrated metal compound is a compound having a decomposition-starting temperature of 150° to 450° C. and represented by the general formula M m  O n . XH 2  O wherein M is a metal; m and n are each an integer of 1 or more determined by the valency of the metal; and X is the number of molecules of bound water or a double salt containing said compound. 
     
     
       6. A flame-retardant olefinic resin composition according to claim 5, wherein the hydrated metal compound has been subjected to surface treatment with at least one silane coupling agent, silicone derivative, fatty acid or fatty acid metal salt. 
     
     
       7. A flame-retardant olefinic resin composition according to claim 6, wherein the silane coupling agent is represented by the general formula RR'SiY 2  wherein R is an organic functional group; Y is a hydrolyzable organic group; and R' is a monovalent hydrocarbon group other than unsaturated aliphatic hydrocarbon groups or is same as Y. 
     
     
       8. A flame-retardant olefinic resin composition according to claim 6, wherein the silicone derivative is modified organopolysiloxane obtained by substituting a part of dimethyl polysiloxane with a modifier group. 
     
     
       9. A flame-retardant olefinic resin composition according to claim 6, wherein the fatty acid is a monobasic carboxylic acid represented by the general formula RCOOH wherein R has a saturated or unsaturated chain structure of 3 to 40 carbon atoms. 
     
     
       10. A flame-retardant olefinic resin composition according to claim 6, wherein the fatty acid metal salt is an alkali metal salt of a monobasic carboxylic acid represented by the general formula RCOOH wherein R has a saturated or unsaturated chain structure of 3 to 40 carbon atoms and is represented by the general formula RCOOM wherein R has the same definition as above and M is an alkali metal atom. 
     
     
       11. A flame-retardant olefinic resin composition according to claim 5, wherein the M is selected from the metals of groups IA, IIA, IIB, IIIA, IVA and IVB of the periodic table. 
     
     
       12. A flame-retardant olefinic resin composition according to claim 11, wherein the M is selected from the metals of group IIA of the periodic table. 
     
     
       13. A flame-retardant olefinic resin composition according to claim 11, wherein the M is selected from the metals of group IIIA of the periodic table. 
     
     
       14. A flame-retardant olefinic resin composition according to claim 5, wherein the hydrated metal compound is magnesium oxide dihydrate. 
     
     
       15. A flame-retardant olefinic resin composition according to claim 5, wherein the hydrated metal compound is aluminum oxide trihydrate. 
     
     
       16. The flame-retardant composition of claim 1, wherein said components (1) and (2) are reacted by kneading component (2) into component (1). 
     
     
       17. The flame-retardant composition of claim 1, wherein said components (1) and (2) are reacted in the absence of external water. 
     
     
       18. The flame-retardant composition of claim 1 wherein components (1) and (2) are reacted in the absence of both a free-radical generator and a catalytic accelerator. 
     
     
       19. The flame-retardant olefinic resin composition of claim 18, wherein components (1) and (2) are reacted in the absence of external water.